1. Field of the Invention
The present invention relates to a mask pattern inspection method, an exposure condition verification method, and a manufacturing method of a semiconductor device.
2. Related Background Art
In inspection of a photo mask substrate, there is a defect which cannot be detected by a mask inspection unit. This defect inspection includes, for example, the inspection of a phase shifter defect, the inspection of a transmittance defect and the inspection of an optimum degree of an OPC shape of a photo mask. As to such inspection, instead of directly inspecting a mask pattern, a method is adopted which uses an optically developed image or a secondary electronic image obtained by once transferring the mask pattern onto a resist on a wafer through exposure and by irradiating this transferred pattern with light or an electron beam. In recent years, as a design rule becomes minute, there especially increases the need of inspection by the electron beam which is advantageous for high-resolution inspection.
However, the resist pattern inspection by the electron beam has a problem that detection sensitivity remarkably deteriorates because of strain or contrast deficiency of a pattern image due to charging of the resist. Especially in inspection of a multilayered resist structure for etching with a high aspect ratio, the whole surface of a wafer is coated with a comparatively thick insulating film, and therefore, the problem becomes more serious.